Capnometer

Abstract

We describe a capnometer for analysing respiratory system function of a patient, the capnometer comprising: a memory to store patient data which is specific to said patient; and a signal processor to analyse a CO 2 waveform representing a variation over time in a CO 2 level of air inhaled and/or exhaled by said patient.

The invention claimed is: 
     
       1. A capnometer for analyzing respiratory system function of a patient, the capnometer comprising:
 an air flow region through which air from said patient's respiratory system passes; 
 an emitter configured to emit light, said emitter comprising a mid-IR semiconductor emitter configured to provide said emitted light at a wavelength in the range 3-5 μm; 
 a reflector to reflect said emitted light; 
 a detector to detect said emitted light, said detector comprising a mid-IR semiconductor detector; 
 wherein said emitter and said detector are arranged such that light from said emitter passes through said air flow region to said detector; 
 a memory to store patient data which is specific to said patient; and 
 a signal processor coupled to said detector to analyze a CO 2  waveform representing a variation over time in a CO 2  level of air inhaled and/or exhaled by said patient, 
 wherein one or more parameters of said respiratory system function are extracted from said patient data, 
 wherein a comparison between said waveform and one or more of said waveforms which were obtained previously for said patient defines a metric with a baseline, wherein said comparing comprises monitoring a deviation of said waveform from said baseline, and wherein said metric is specific to a disease or type of disease of said patient, 
 wherein said one or more parameters comprises rise and fall time of a CO 2  level, 
 wherein said air flow region comprises one or more alignment pins incorporated into a breathing tube, and 
 wherein said one or more alignment pins enable alignment of said reflector with said emitter and said detector. 
 
     
     
       2. A capnometer as claimed in  claim 1 , wherein said patient data comprises identification data of said patient. 
     
     
       3. A capnometer as claimed in  claim 2 , wherein said identification data comprises one or more of an identification code, fingerprint data, iris scan data and patient respiratory profile data. 
     
     
       4. A capnometer as claimed in  claim 1 , wherein said signal processor is configured to provide a CO 2  level data output defining said CO 2  waveform, and wherein said CO 2  level data output is stored in said memory or a second memory internal or external to said capnometer for later interrogation. 
     
     
       5. A capnometer as claimed in  claim 4 ,
 wherein said signal processor is further configured to use said CO 2  level data output to determine compliance data identifying episodes when a drug has or has not been taken by said patient, and to determine compliance with a drug taking regime from said compliance data, and 
 
       wherein said determination of said compliance with said drug taking regime comprises one or more of:
 determining whether said patient uses said capnometer to obtain said CO 2  level data output; 
 determining, based on said waveform, whether said patient takes said drug; 
 determining whether said patient takes said drug based on drug use data provided by said patient at a drug use data input of said capnometer; and 
 determining whether said drug has been dispensed from said capnometer. 
 
     
     
       6. A capnometer as claimed in  claim 1 , wherein said signal processor is configured to analyze said respiratory system function responsive to one or more of: a shape of said waveform, one or more peak heights of said waveform, an amplitude or amplitude variation of said waveform, and a frequency composition of said waveform. 
     
     
       7. A capnometer as claimed in  claim 1 , further comprising one or more user indicator devices, wherein, based on said waveform, said user indicator devices indicate a quality of said respiratory system function. 
     
     
       8. A capnometer as claimed in  claim 7 , further comprising an alarm and/or messenger configured to be triggered dependent on said indication of said quality of said respiratory system function. 
     
     
       9. A capnometer as claimed in  claim 7 , wherein said processor is further configured to indicate when a therapeutic intervention is required based on said quality of said respiratory system function. 
     
     
       10. A capnometer as claimed in  claim 1 , wherein said signal processor is configured to determine from said waveform one or more of:
 a first indication of a point in time when a drug has been taken; 
 a second indication of a point in time when a drug should be taken; 
 a third indication of a type of drug which has been taken; 
 a fourth indication of a type of drug which should be taken; 
 a fifth indication of a dose which has been taken; 
 a sixth indication of a dose which should be taken; and 
 a seventh indication that a drug has expired and/or has been used up. 
 
     
     
       11. A capnometer as claimed in  claim 10 , further comprising a medical drug dispensing system for controlling a release of a said drug responsive to a said determination, wherein said medical drug dispensing system is configured to automatically release a said drug and/or control a said type and/or dose and/or point in time of said release of a said drug. 
     
     
       12. A capnometer as claimed in  claim 10 , wherein said signal processor is further configured to determine when said drug should be released during a breath cycle. 
     
     
       13. A capnometer as claimed in  claim 1 , wherein said signal processor is further configured to determine, from changes in said waveform over time during a single use of said capnometer by said patient, a variation in a condition of said respiratory system function. 
     
     
       14. A capnometer as claimed in  claim 1 , further comprising a wellbeing data input for allowing said patient to input wellbeing data, said wellbeing data describing a health status of said patient, wherein said processor is further configured to process said wellbeing data in combination with a detector signal to determine an effect of a drug on said patient. 
     
     
       15. A capnometer as claimed in  claim 1 , wherein the capnometer is configured to be part of an inhaler. 
     
     
       16. A system comprising:
 the capnometer of  claim 1  or the capnometer of  claim 15 ; and 
 an analysis system in communication with said capnometer, 
 wherein said analysis system comprises an analysis system memory to store said patient data; and 
 wherein said analysis system is configured to: 
 i) modify an indicator setting of an indicator of said capnometer, wherein said indicator indicates a quality of said respiratory system function; and/or 
 ii) change a dose level of a drug dispensed using said capnometer; 
 wherein said analysis system is further configured to transfer said modified indicator setting and/or changed dose level to said capnometer for storage in the memory of said capnometer, wherein data stored in said memory of said analysis system further comprises patient data specific to further patients, and wherein said modification of said indicator setting and/or change of said dose level are further dependent from said patient data specific to said further patients. 
 
     
     
       17. A method of monitoring patient compliance with a drug-taking regime, the method comprising:
 monitoring CO 2  levels in exhaled breath of the patient with a capnometer as claimed in  claim 1 ; 
 storing data from said monitoring; 
 using said stored data to determine compliance data identifying episodes when said drug has or has not been taken; and 
 determining compliance with said drug taking regime from said compliance data, and wherein said compliance data further identifies a dose which has been taken. 
 
     
     
       18. The capnometer of  claim 1 , wherein said deviation of said waveform from said baseline is used to determine an indication selected from the group consisting of: a point in time when a drug has been taken, a point in time when a drug should be taken, a type of drug which has been taken, a type of drug which should be taken, a dose which has been taken, a dose which should be taken, a drug that has expired and/or been used up, and combinations thereof. 
     
     
       19. The capnometer of  claim 1 , wherein said comparison is specific to said patient, and based on one or more variables specific to said patient. 
     
     
       20. The capnometer of  claim 1 , wherein said air flow region comprises a mid-IR transmissive portion aligned with said emitter and said detector to allow mid-IR light to pass through said transmissive portion into, and out of, said air flow region, and
 wherein said mid-IR transmissive portion comprises a coating that increases an efficiency of collection of said emitted light on to said detector. 
 
     
     
       21. The capnometer of  claim 20 , wherein said mid-IR transmissive portion comprises a separate window. 
     
     
       22. A capnometer for analyzing respiratory system function of a patient, the capnometer comprising:
 an air flow region through which air from said patient's respiratory system passes; 
 an emitter configured to emit light, said emitter comprising a mid-IR semiconductor emitter configured to provide said emitted light at a wavelength in the range 3-5 μm; 
 a detector to detect said emitted light, said detector comprising a mid-IR semiconductor detector; 
 wherein said emitter and said detector are arranged such that light from said emitter passes through said air flow region to said detector; 
 a memory to store patient data which is specific to said patient; and 
 a signal processor coupled to said detector, said signal processor configured to analyze said respiratory system function responsive to one or more parameters of a CO 2  waveform that represents a variation over time in a CO 2  level of air inhaled and/or exhaled by said patient, 
 wherein said one or more parameters is selected from the group consisting of: a shape of said waveform, one or more peak heights of said waveform, an amplitude or amplitude variation of said waveform, a frequency composition of said waveform, and combinations thereof, 
 wherein a comparison between said waveform and one or more of said waveforms which were obtained previously for said patient defines a metric with a baseline, wherein said comparing comprises monitoring a deviation of said waveform from said baseline, and wherein said metric is specific to a disease or type of disease of said patient, 
 wherein said signal processor is further configured to: 
 (i) determine from said waveform one or more of:
 a first indication of a point in time when a drug has been taken; 
 a second indication of a point in time when a drug should be taken; 
 a third indication of a type of drug which has been taken; 
 a fourth indication of a type of drug which should be taken; 
 a fifth indication of a dose which has been taken; 
 a sixth indication of a dose which should be taken; and 
 a seventh indication that a drug has expired and/or has been used up, and 
 
 (ii) determine, from changes in said waveform over time during a single use of said capnometer by said patient, a variation in a condition of said respiratory system function, 
 wherein said air flow region comprises one or more alignment pins incorporated into a breathing tube, wherein said one or more alignment pins enable alignment of a reflector with said emitter and said detector. 
 
     
     
       23. The capnometer of  claim 22 , further comprising:
 a medical drug dispensing system for controlling a release of a said drug responsive to a said determination, 
 wherein said medical drug dispensing system is configured to automatically release a said drug and/or control a said type and/or dose and/or point in time of said release of a said drug, 
 wherein said signal processor is further configured to: 
 (i) determine when said drug should be released during a breath cycle, and 
 (ii) determine compliance data identifying episodes when a drug has or has not been taken by said patient, and to determine compliance with a drug taking regime from said compliance data, and wherein said determination of said compliance with said drug taking regime comprises one or more of:
 determining whether said patient uses said capnometer to obtain said CO2 level data output; 
 determining, based on said waveform, whether said patient takes said drug; 
 determining whether said patient takes said drug based on drug use data provided by said patient at a drug use data input of said capnometer; and 
 determining whether said drug has been dispensed from said capnometer. 
 
 
     
     
       24. A capnometer for analyzing respiratory system function of a patient, the capnometer comprising:
 an air flow region through which air from said patient's respiratory system passes; 
 an emitter configured to emit light, said emitter comprising a mid-IR semiconductor emitter configured to provide said emitted light at a wavelength in the range 3-5 μm; 
 a detector to detect said emitted light, said detector comprising a mid-IR semiconductor detector; 
 wherein said emitter and said detector are arranged such that light from said emitter passes through said air flow region to said detector; 
 a plurality of additional emitters, wherein each of said plurality of additional emitters emits light at a different respective wavelength, wherein each of the different respective wavelengths is within a detection range of said detector, and wherein, during an inspiration and/or an expiration of said patient, said plurality of additional emitters pulse such that said light from each of said plurality of additional emitters is detected by said detector at a different respective point in time; 
 a memory to store patient data which is specific to said patient; 
 a signal processor coupled to said detector to analyze a CO 2  waveform representing a variation over time in a CO 2  level of air inhaled and/or exhaled by said patient; 
 wherein a comparison between said waveform and one or more of said waveforms which were obtained previously for said patient defines a metric with a baseline, 
 wherein parameters of said respiratory system function are extracted from said waveform, said parameters comprising: a shape of said waveform, one or more peak heights of said waveform, an amplitude of said waveform, an amplitude variation of said waveform, rise and fall time of a CO 2  level, a slope of said CO 2  level versus time, and a frequency composition of said waveform, 
 wherein said signal processor determines that a measurement of said inspiration and/or said expiration of said patient is void when a scattering of light emitted by said plurality of additional emitters correlates between at least two emitters in said plurality of additional emitters at one of the different respective points in time, and 
 wherein said signal processor corrects a signal from said detector when said measurement is void.